1. Field of the Invention
This invention relates to a surgical instrument and method for developing a "minimally invasive" accessway to a surgical objective in the interior of the body by dissecting tissues along planes of lower resistance. The invention further relates to dissection and retraction of tissue to provide an adequate depth of field for fiberoptic viewing.
2. Description of the Prior Art
Surgeons in the past have used blunt-tipped instruments as well as balloons in connection with endoscopic surgery to dissect tissue in order to develop a working space in the interior of the body. Typically, the development of such a working space is done blindly or under endoscopic viewing only if at least one accessory port or accessway is established. To perform a surgery in such a working space, the working space is maintained by insufflation with carbon dioxide gas which provides room for viewing with an endoscope as well as room for manipulating accessory instruments. To introduce such accessory instruments into the working space, additional incisions typically are made by plunging a sharp-tipped trocar through the distended body wall overlying the insufflated working space.
It has been found that it may be undesirable to dissect accessways and anatomic spaces blindly. It also has been found that it may be difficult to make additional incisions into a dissected anatomic space particularly if of limited volume or if overlying delicate anatomic structures. It also has been found that insufflation of a working space with carbon dioxide causes tissue emphysema which may be undesirable for particular patients because of excessive carbon dioxide absorption into the blood, thus making a "minimally invasive" endoscopic approach unsuitable.
An illustrative example of a procedure that cannot be performed endoscopically under conventional practice is the division of a nerve along the spinal column. An open surgical approach to the division of such a nerve also is undesirable because it is time consuming and results in excessive postoperative pain and recovery time as well as resulting in a disfiguring six inch incision along the patient's spine. There is therefore a need for new instruments and methods for developing a "minimally invasive" accessway to the interior of the body and for performing a surgery under direct fiberoptic vision within the interior of the body, and particularly for accomplishing an endoscopic division of a nerve along the spinal column.